tonight, the stunning new video showing how that convicted killer escaped from a pennsylvania prison. the new images, the inmate crab-walking up a wall from the prison exercise yard to break

out as the manhunt for him stretches to nearly a week. where were the guards, and the new sighting, where was he last seen? and the other manhunt tonight in washington, d.c. after a murder suspect escaped from a hospital. just in, president biden's son hunter expected to be indicted by the special counsel investigating him after his plea deal collapsed. what are the charges? a federal judge ordering texas to remove that floating border barrier in the rio grande. how the state is responding. the rise in covid cases and our exclusive nbc news reporting, could the fda authorize updated boosters this week? hurricane lee just forming in the atlantic. will it impact the u.s.? al roker is here with the latest track. the dangerous september heat wave breaking records from the south to the northeast. schools forced to make tough choices. the video of a russian missile strike on a ukraine market happening just as secretary of state tony blinken made a surprise visit to kyiv.

and the young americans shining at the u.s. open. they've already made history. can they win it all? >> announcer: this is "nbc nightly news" with lester holt. good evening, and welcome, everyone. how did a convicted killer simply walk free from a pennsylvania prison? apparently horizontally. that's what just released security video of danelo cavalcante's escape a week ago appears to show. the five foot 120-pound inmate suspended face down between two walls quickly walking himself to the roof of the chester county prison where he made his getaway, unseen by a guard in a nearby tower. a vulnerability prison officials were aware of after the prior escape attempt of another inmate. the new details adding to the frustration and anxiety of residents who have been living through an active police manhunt these last seven days for an escapee considered dangerous.

our george solis is there now with the very latest. >> reporter: this is the moment danelo cavalcante began his escape from the pennsylvania chester county prison early thursday morning. officials today releasing the video and describing how the convicted killer crab-walked up a wall by the prison's exercise yard before pushing his way through razor wire. >> while we believe the security measures we had in place were sufficient, they've proven otherwise. >> reporter: the prison's acting warden acknowledging cavalcante escaped undetected even though the prison's observation tower was staffed at the time. >> the tower did not observe or report the escape. the escape was discovered as part of the inmate counts when inmates come in from the exercise yard. >> reporter: the officer stationed in the tower, he said, is now an administrative leave. the warden said cavalcante made his escape at 8:51 a.m. but he wasn't determined to be missing from the prison for nearly a full hour.

>> the prison was locked down, and the count was conducted. by 10:01 the siren had sounded, and the 911 center had been notified. >> reporter: it mirrored an escape from may when court documents say igor bolte climbed to a visitor entrance where there was less security and captured within five minutes, and security measures were added to the prison. authorities now adding even more. >> fully enclosing all outside exercise yards and installing more cameras and adjusting sites. >> reporter: police say they believe cavalcante is now heading south confident he has not escaped their perimeter. >> we're committed to the search, and we will find him. we will bring him back and into the criminal justice system. >> and, george, questions have been raised about the escape since it happened thursday last week. so, how did authorities explain why they decided to address it now? >> reporter: yeah, lester, i asked

officials point plank why they didn't release any details or that video sooner. they said it was the decision of the state attorney general's office also investigating the escape adding, they wanted to focus on the capture of the fugitive, lester. >> george, thank you. there is another manhunt we're following this evening in washington, d.c. police say murder suspect christopher haines escaped from custody at george washington university hospital this afternoon. that prompted the university to issue a shelter in place order for the campus. police are asking the public for tips to help find him. also breaking this evening, federal prosecutors say they will now seek an indictment of the president's son hunter biden just as republicans ramp up their own investigations. senior legal correspondent laura jarrett is here. laura, explain the timing. why now? we knew there were charges afoot. >> it seems as though it's still headed in the direction of trial, lester, but for the first time, the special counsel, david weiss, announced he does plan to seek a grand jury indictment of the president's son hunter by the end of this month.

that new timing is largely driven by biden's rights to a speedy trial. now, the precise charges, those are still unclear, but this comes after weiss had negotiated that plea deal allowing hunter biden to avoid prison time for illegally buying a gun while using drugs and failing to pay his taxes on time. you'll remember that deal fell through. under a judge's scrutiny in july. biden then pleaded not guilty. meantime, republicans have blasted weiss for what they call a sweetheart deal pressing weiss for more information. the real question is whether prosecutors only charge him for the gun and the tax issues that we already know about or whether he's in greater jeopardy on his foreign business dealings. now, biden's attorneys say they believe at least some part of this deal is still valid, lester. >> all right, laura, thank you. in texas tonight, a federal judge has ordered the removal of those controversial buoys placed in the rio grande by the texas governor to deter migrants from reaching the united states. miguel almaguer has more on this.

miguel, what did the judge say about this? >> reporter: well, lester, the federal judge is ordering officials in texas to move that controversial floating barrier to the riverbank in what's a clear victory for the biden administration, at least for now. installed over the summer, the wrecking ball-size buoys created a long water barrier where migrants often tried to cross the rio grande from mexico. critics say the barrier raised humanitarian concerns fearing it could cause some to drown. the u.s. justice department accused texas of installing a barrier on the international boundary without permission. now, a judge says the barrier must be moved to the riverbank by the end of next week. texas governor greg abbott says the state will appeal and is prepared to fight today's ruling all the way to the supreme court. lester. >> miguel almaguer tonight, thank you. you may have noticed cases of covid are ticking up again. nbc news has learned that new vaccine booster shots could be available next week after cdc approval, even as many have put covid in the rearview mirror.

here's tom costello. ♪♪ >> reporter: the american seniors are in ireland to soak in irish music. they got the music, but 6 out of 20 also got covid. >> i didn't want to spend my whole vacation wearing a mask in ireland. you can't sing along with a band with a mask on. >> reporter: frances foster's third bout with covid is milder but she is isolating in a dublin hotel room. >> i had a bad day yesterday. today i seem better. >> reporter: new cases are popping up around the world and across the u.s. including first lady dr. jill biden. president biden criticized for removing his mask while awarding the medal of honor to an 81-year-old veteran. after 150,000 hospitalizations in january, that dropped to 6,300 in june. the cdc reports hospitalizations are rising again. more than 17,000 as of august 26th, far below pandemic levels but a

reminder, say experts, covid may be here to stay. >> the sickest covid patients are certainly older, immunocompromised and have primary pulmonary disease and are diseases like emphysema and are unvaccinated. >> reporter: the fda now expected to approve updated covid boosters as soon as friday. available as soon as midweek. moderna and pfizer say their new vaccines appear effective against the new ba-2.86 variant, which has appeared in michigan, new york, ohio, and virginia. meanwhile, health agencies report an uptick in the rsv virus common in children, especially now in florida and georgia. the fda recently approved a new rsv vaccine for small children and expectant mothers. >> and, tom, back to covid for a moment. what are health experts telling people about testing? >> reporter: yeah, you know those test kits that many people still have in their homes, they should pick up the newest covid variants, and even if that test has expired,

it may still be viable. the fda has been extending the expiration dates. you can check whether yours is still valid on the fda's website. lester. >> all right, thank you. the senate's top republican mitch mcconnell addressed questions about his health today playing down concerns over transparency including from a few members of his own party, saying he plans to complete his term. ryan nobles has that story. >> reporter: tonight after two freezing episodes in less than two months -- >> i'm sorry, we're going to need a minute. >> reporter: mitch mcconnell insisting there is no reason for him to step down. >> i'm going to finish my term as leader and i'm going to finish my senate term. >> reporter: pressed about his healths, the 81-year-old saying his doctor's report said everything. >> what dr. monahan's report addressed was concerns people might have that should things happen to me did happen -- well, they didn't. i think he pretty well covered the subject. >> reporter: the

capitol attending physician examined mcconnell writing, quote, there's no evidence that you have a seizure disorder or that you've experienced a stroke. tia, or movement disorder such as parkinson's disease. >> how are you feeling? >> reporter: the doctor attributed the spells to dehydration and a concussion mcconnell suffered back in march when he fell and also fractured a rib. tonight, most senate republicans are satisfied. >> i think his health is sound, and his leadership is as good as it's been in the 8 1/2 years i've been here. >> reporter: but not all republicans are on board including rand paul, who is an ophthalmologist. >> i practiced medicine for 25 years and doesn't look like dehydration but a focal neurologic event. >> reporter: paul saying he's not questioning mcconnell's ability to handle his job. age now a major political issue. some democrats have called on 90-year-old senator dianne feinstein to resign, and voters also have concerns about 80-year-old president biden. a recent poll finding 77% of americans including 69% of democrats think the president is too old

to serve another term. and in a closed door lunch with his fellow republicans, mcconnell talked about his health but took no questions. his caucus remains behind him as their leader. lester. >> all right, ryan, thanks. in ukraine one of the deadliest russian attacks in months. at least 17 people killed at a market as secretary of state antony blinken arrived in kyiv. richard engel is there for us tonight. >> reporter: the people shopping here were calm and unsuspecting. the first sign they had of danger was the terrible whistle of incoming, but by then it was too late. 17 were killed by the russian missile including a child. many more were wounded. ukraine doesn't have enough air defense systems to cover the entire country and depends largely on u.s. military aid for protection. just hours earlier, secretary of state blinken arrived in kyiv, his first visit since ukraine launched a major counteroffensive against russian forces three months ago.

he met president zelenskyy. >> tough period for our society. >> reporter: with ukraine's airspace unsafe, blinken arrived by overnight train from poland. blinken today announced another $1 billion in aid. >> we're committing to helping ukraine build a force for the future. >> reporter: both ukraine and russia are running low on ammunition, but russian president putin may soon get a resupply from north korea's dictator kim jong-un. he has vast stockpiles of just what russia needs now. >> ukrainians are fighting for their own country, for their own future, for their own freedom. russians are not, and that gives me tremendous confidence that ukraine will prevail. >> reporter: ukraine's counteroffensive has been extremely slow-going as troops try to break through heavily fortified russian positions, but secretary blinken said tonight, it is starting to show progress. lester. >> richard engel in kyiv, thank you. and tomorrow

richard will have an exclusive interview with secretary blinken in ukraine. in 60 seconds, tropical storm lee becomes a hurricane. al roker tracking what is poised to be a major storm and how the summer heat stretching into september is forcing schools to make tough choices next. e knew that i as want to know more about my family history. with ancestry i dug and dug until i found some information. i was able to find out more than just a name. and then you add it to the tree. i found ship manifests. birth certificate. wow. look at your dad. i love it so much to know where my father work, where he grew up. it's like you discover a new family member. discover even more at ancestry.com the virus that causes shingles is sleeping... in 99% of people over 50. it's lying dormant, waiting... and could reactivate. shingles strikes as a painful, blistering rash that can last for weeks. and it could wake at any time.

think you're not at risk for shingles? it's time to wake up. because shingles could wake up in you. if you're over 50, talk to your doctor or pharmacist about shingles prevention. tonight, much of the country remains in the grip of an unusual september heat wave while tropical storm lee has just become a hurricane. al roker is tracking it. this could be a big one. >> it actually can be, lester. in fact, we're expecting it to become a major hurricane right now with 75-mile-per-hour winds about almost 100 miles east of the northern leeward islands moving northwest at 14 miles an hour. by saturday it's a category 4 storm with 150-mile-per-hour winds. we're going to continue to watch it over the weekend. it remains north of puerto rico. right now from the southwest to the northeast, 85 million people under heat advisories along the east coast, records tomorrow for hartford, salisbury, jacksonville, baton rouge, dallas

but this cold front will bring relief over the weekend to the northeast. temperatures drop below normal, and look at this, new york all the way to buffalo, cleveland, chicago, and st. louis all with average temperatures, but to the south, unfortunately, the heat wave continues into next week for mobile, baton rouge, houston, triple digits for san angelo, dallas, san antonio and very close to corpus christi. lester. >> all right. al, thanks very much. and the severe heat is causing major disruptions tonight, especially for children as they begin the new school year. let's get more on that from cbs' kristen dahlgren. >> reporter: across the country, the start of school had students sweating, quite literally. >> we're just drowning in our sweat because it was so hot. >> reporter: the late season heat wave leaving classrooms and school buses sizzling forcing administrators to pivot. in philadelphia that meant early dismissal. some parents not pleased. >> i want to know why these schools don't have ac when our tax money i mean pay for all this. >> reporter: in

worcester, massachusetts, the district says more than three-quarters of schools don't have air-conditioning. >> i brought like a mini fan that you plug into your phone. i used that all day. >> reporter: pittsburgh was back to virtual for a second day leaving mom lisa murphy with three kids at home. >> my work is on pause, things around the house don't get done, errands don't get run because i can't leave the house with three kids online. i really hope they go back tomorrow. >> reporter: 85 million americans spent the day under heat alerts in a week that has already seen dozens of temperature records shattered. even in new england temperatures were just too high to have some sport practices. >> all right now we're over 86.2, so right now we have no outdoor activities are allowed. >> everything would be canceled. >> yeah, exactly. >> reporter: september is late in the season for a heat wave here, but the world meteorological organization says it comes after the hottest august on record. the second hottest month ever right behind this july. kristen dahlgren, nbc news, manchester, new hampshire.

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the horror. >> reporter: they're among more than 400,000 people who have escaped from the civil war in sudan that erupted four months ago. we visited a makeshift camp there today with u.n. ambassador linda thomas-greenfield, who wanted to hear firsthand what they've experienced. >> and these are your two grandchildren. >> no food, no drinks. >> reporter: this woman fled after their older brother was killed by the militias. their home destroyed. what do you hope for? >> we need the peace. >> reporter: she feared being targeted because she is a lawyer, so she fled. >> i'm afraid. >> you're afraid. >> yes. >> reporter: this doctors without borders hospital care for the sick including a recent measles epidemic and starving children. >> it is overwhelming. i see those little children. i saw a 6-month-old who looked like a newborn, and i was told by the doctors that actually she was doing better. >> reporter: you can hear the pains and

the terror they've experienced. many of the women in this makeshift camp tell of being raped by the marauding militias, who kill the men and steal the boys. it has led the u.n. to investigate a possible genocide. they're reporting mass graves, and i went to the darfur region in 2005 with secretary of state condoleezza rice. that was declared a genocide. 18 years later history is repeating itself, and the leaders of the previous horrors have still not been brought to account. >> now we are seeing the evidence of it starting again. what we see happening in darfur right now portends to what we saw happening in darfur in 2004, so we have gone backward in those years. >> reporter: the u.n. says it needs a billion dollars more to feed, house and heal the refugees, and so far has raised only a third of that, hardly enough to deal with the tragedy.

but today the ambassador did sanction some militia leaders for mass atrocities and another $163 million in aid with no end in sight for the war and a flood of its desperate victims. andrea mitchell, nbc news, chad. >> and we will continue to follow the story as if evolves. we'll take a break here. up next, the new generation of americans dominating the world stage at the u.s. open. -whoo-hoo! -[ laughs ] well done, ma'am. what...did i do exactly? with snapshot from progressive, you get a personalized discount for doing exactly what you're already doing -- being a safe driver. congratulations. this is a bowling trophy. yeah, it's the biggest one they had. okay, thanks. mm-hmm. oh. have a good one. it's started. it's... the side hug. tween milestones like this may start at age 9. hpv vaccination—a type of cancer prevention

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finally tonight the thrilling action at the u.s. open and the young black american stars making history on one of the sport's biggest stages. here's rehema ellis. >> reporter: coco gauff back on a steamy court today playing doubles. the 19-year-old will lay in the singles semifinal tomorrow, the first american teen to make it this far at the u.s. open since serena williams. >> she's my idol, and i think if you told me when i was younger that i would be in the same, like, stat lines as her, i would freak out. >> reporter: gauff just one of the young american stars making a splash at this year's tournament. >> i'm so proud. >> what do you think about all the young americans that are doing so well this year? >> they just have the power. they have the confidence. they have what it takes to get to the top. >> game, set and match. >> reporter: overnight 20-year-old ben shelton punched his ticket to the semis upsetting fellow american frances tiafoe. >> sometimes you got to shut off your brain, close your eyes and swing. >> reporter: it marked

the first time two black men have ever opened in a u.s. open quarterfinal. >> i love to see american tennis going in a great direction. >> reporter: shelton, who has a 149-mile-per-hour serve in his arsenal, will face novak djokovic next looking to break the 20-year drought since an american man has won it all. >> i'm definitely going to try to, you know, bring some things to the table that are different and hopefully disruptive. >> reporter: the next generation of american tennis has officially arrived. rehema ellis, nbc news, new york. that's "nightly news" for this wednesday. thank you for watching. i'm lester holt. please take care of yourself and each other. good night. good night.

we have some breaking news at this hour. firefighters on the scene of a vegetation fire in lake county. this is near highway 29 and clayton creek road.